Automatic screw and nut release



H. F. CLARK AUTOMATIC soREw AND NUT RELEASE m 1 9 5, l l L, w. 3 M v. ,w a n M F t 2 shetssheet 1 EVV /VVV/ www @ggg 2^ MIT IN VEN TOR.

H. F. CLARK AUTOMATIC SCREW AND NUT RELEASE 2 Sheets-Sheet 2 MN 1 9 5, 11 1 L. w 3 M v. m a n M F i5 IN V EN TOR.

-lidwm walk Patented May 31, 1949 UNITED STATES PATENT OFFICE AUTOMATIC SCREW AND NUT RELEASE Harry F. Clark, Oakwood, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application May 15, 1946, Serial No. 669,822

16 Claims.

`direction under the iniiuence of that or another force. One of such applications is an aircraft machine gun which needs to be cocked against the tension of a spring in the event of a failure to fire. This cooking could be done by a nut and a screw driven by a reversing electric motor. However, reversing electric motors are heavy and more expensive than Single direction motors and require a more complicated and expensive form of control. Moreover, the time required to reverse the motor and return the nut is substantially as great as to move the nut in the opposite direction against the force. The friction in an ordinary screw and nut combination is very high, so that the load upon the m-otor is much higher than that necessary merely .to overcome the force.

It is an object of my invention to provide a nut and screw combination having low friction wherein the nut can be released from the screw.

It is another object of my invention to provide a ball bearing type nut and screw combination with an automatic releasing means.

It is another object of my invention to provide a ball bearing type nut and screw combination with an automatic release which will be released at one end of a traverse and be re-engaged at the opposite ends thereof.

As an example I have shown an electrical machine gun charging or cooking device which automatically cocks thegun in the event a cartridge fails to fire. To do this in the most economical manner. I have provided a single direction electric motor which drives a long screw provided with a ball bearing nut. A time delay switch, normally kept open by the normal operation of the gun, is provided for closing the circuit to the electric motor when the machine gun stops firing with the bolt in its forward position. This causes the motor to turn the screw to cause the nut Vto move rearwardly along the screw and1 carry the bolt to its rearward position where it may be latched by the sear. As the nut moves lfrom its forward to its rearward position it compresses a spring which is used to propel the bolt to the firing position. The nut is automatically released from the screw by removing a portion of the ball race so that when the bolt is released the nut will be returned to its forward position 35 jections at 28 and 30 with the bushing 32.

50 type screw 52.

(Cl. 'i4-2) along with the bolt under the force of the spring without further operation of the motor.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. l-A is the rearward horizontal section.

and Fig. l-B is the forward horizontal section of a machine gun charging or cocking device,

' together with a portion of the bolt mechanism;

Fig. 2 is a sectional view taken along the line 2-2 of Fig. l-B;

l5 Fig. 3 is a top fragmentary view of the charger showing the ball bearing nut in its rearward position;

Fig. 4 is a view showing the balls in the ball race and the two elements forming opposite sides of the ball race; and

Fig. 5 is a View of the cam member forming the periphery of the ball race.

Referring now to the drawings and more particularly to Fig. 1-A, there is shown the bolt 20 of an aircraft machine gun being held in its reartion shown. This portion of the gun is shown on a reduced scale as compared with the portion of the machine gun charger proper shown in the upper portion of the iigure. The bolt 20 is connected through the interconnecting pro- This bushing 32 surrounds the compression coil spring 34 which provides the force for forcing the bolt il .into the firing position. As shown in Fig. i--B, the bushing 32 has an inturned :flange 35 supporting one end of the coil spring 34 while der ill provided with a gear meshing. with a rack to operate the cartridge fitting mechanism. Y The housing 40 supports a single direction electric motor 45 which. through the coupling 48 and the shaft extension 50, drives the ball bearing The other end of the ball bearing type screw 52 is mounted in a bearing 54 supported by the housing of the gun. The screw 52 is surrounded by a sleeve 56 provided with long straight slots `6l] and 62 on its opposite sides.

55 Shown at the forward end of its traverse is my releasable ball' bearing nut which includes the housing 58 having key projections |54 and 66 on the opposite sides thereof which t against the top edge of each of the slots G and 62 in the sleeve 55 and which have their outer surfaces flush with the outer surface of the sleeve 56. The housing 58 is also provided with square, projections 68 vandf'lil which extend; outwardly from? the key projections 54 and B6.

Locked securely within the ball housing 5B are. the front and rear ball guides 12 and 14 between which are held a sucient numberofgst'eel.ballls 1E to fill the ball race providedin between these. guides. A ball cam 18 has its `cylindrical'portion` fitting over the reduced cylindrical portion of'th'eV front ball guide 12 and has longitudinal projecfront ball guide.

which extend in front of the projections Bill and 1U, but are wider, as shown in Figs. 2 and 3.

The ball cam 18 is axiallymovable and has an inwardlybeveledA cam edge which has its major portion in the form of a helix beginning at the point` designated by the reference character 83"- and terminating at the point designated-byv the reference character 9i). This beveledface in the form of a helix is identical to the helix ofv the screw 52 Between the. points S8 andg 'there is provided a recess 92:' likewise inwardly beveled. Through the intertting of the projections BUand 82"with the slots 84 and 86' in thefront ball guide` 12, the .ball cam 18 is always,kept'orientatedwith respect to the front ball guide'l'A and the. rear ball guide 14 are kept in orientationv by th'epin slots 93. and 94 by which they are pinned to the housing by pins, such as thepin ishownin Fig. 2.

The front ball guide,12' has themajor portion of its rearward edge in the.fo1rn. of a helix beginning at the point Stand endingat ,the pointl |,2|. Likewise the forward edge of therear ba'll guide is in. the form of aV helix beginning at -the point |23 and ending at the point..|25. These` helical surfaces are identical to the helices of the screw 52; ,Between the-endsof these. helices isa return path which kallows the balls. toreturn from the end of the helix. to-the beginningof the helix of this race provided between-thefront and. rear ballguides. return path when. the Aballcam-is in theposition shown in Fig. l-Bl.

When. the ball cam .18 is movedto. cover. theball. race, the inwardly .beveledy surfaces upon. the helical end of this camlwilllcamthe balls 1.6inY the.helical..portion of the ball racev intotheball grooves of thescrew 52 By. reason. of therecess 92.- the balls asthey leave. the endof. the helical portions of the ball racecan freely pass. over. one of.the.threads. to the 4beginning. of.` the .helical-seca tion ofthe ball race. When theDaIl-.camf'ltiL is in..this position, therotationofthe screw 52 will thread theball bearing nutriti` from the forward end. of the screw 52. to. therearward endofl this screw.. The .balls 16. will rollin the grooves, of' the screw 5E-,as wellasin thepball race provided bythe front1 and rear. ballguidesl andJM on.the.sides.- The periphery of the helical portion. offthe. ball race is for-med by the ball. cani-18.

In the normaloperation of the gun bushing 32, upon the release ofthe sear 22, moves forward under the impetus of the spring 34, to the dot and dash line position indicated by the reference character 32'.' The normal ring of the gunv provides a recoil which sends' the bolt-'20; as well as the These. projections Siland 82" have outwardly turned 'end portions or prongs The recess ,92 registerswiththis.

bushing 32, to its reaimost position. The operation of the gun is controlled by a trigger switch |43 which connects the battery or power supply |45 with the trigger solenoid |41 which is connected to and operates the sear Z2 to release it from latching engagement with the bolt 20. The sear 22, when the trigger solenoid |41 is deenergizecl' operates tof-latch: theibolt inf. its: rearward position. Als soon as the trigger solenoid |41 is energized the sear 22 releases the bolt which moves forward under the impetus of the spring 34e-to causering of the gun. The gun will no1'- mally continue firing until the trigger solenoid |41 isdeeneflgized: .to again latch the bolt 2i) in its rearward position.

However, if va cartridge should fail to nre there Wi'llbeno'vrecoiband the bolt 2G and the bushing 32 will, remain in the forward position illustrated by' the' dot and dash lines indicated by 32. The time delay switch |21 has a pin |49 normally engaged-by the proj ectlon\28t`ocontract,A the bellows |2`9-to'hold thesw-ito'h' bar: ISILinfth'e openwpositionwhenever the' bolt -2U i's n'l` its rearward: pose tion. A check @valve |5'|\I permitswair to'lvesoape from Within Ithe-bellows |251 but closes1to=delay1 the expansion' of the bellowsl Tl'ieloheckf'valvel |52', when closed,--willi'al1ow a sligh-tfhlakageof air into the interior#ofthebellows-IZlli so that Vin' the normal opera-tion ofthe gunftlie expansion o-f'the bellows will be sol slowthat-A the :switch bar |3{2wi1l always be`- kept-in fthe-open-f position. However, if' the gun-stops ring in the forward position the-bellows* |291* lw-illf'- slowly' move-the switch b-ar to closed posi-tionz The time which it` takes the`bellows` |29t to move-fthebar -|3|'\v toclosed positionl is longer than -thefnter-val be'-l tween the reciproca-tions ofthe bolt 253;' l Whenth'e gun' ceases firing in the-fo1'ward-positlon-the interval is long enoughgforthebellowsI |29,"uncl'er the impetus of itsVA internal-spring; tofinovethe switch'- bar |3| to the'closed1position'thereby closing -the circuit,'which includes the electric motor 45, the conductor |33, the time delay switch |21 the conductor |35; the switch |31; the battery or power supply- |39, andthe-conductor |4|l The switch |31 is'closedduring' thegnorrnal operation ofthe gun and opened when the operation of the gun is stopped. This energizes the motor' 46: 1

This will cause the screw'5'2 to berotated and the ballv bearing nut 58 willt bethreaded rearwardly by the screw. -52 carrying theLbushing 32 and the bolt 2D fromitsforwarditoits'rearward position. The .ball camA 18 at; thistime is in its rearward position so thatthe-balls in the helical portion ofthe race are heldin the thread grooves ofY the screw 52. By thisactiomthe nut 5851s carried from the forward' end' of '.thescrew 52 to the rearward lend^with"a minimum of friction. The nut 58 is preventedfrom rotatingxwith the screw by the contactof the key. projectionsd and IEli with theA upper edges of'the'slots G0 and 62f in the sleeve 562 These-slots 60 and 62 are wider than thekey projections 6'4; and' lso; that the out-turned ends of projections.` and 82 of the ball cam 18'can likewise travel through them.

The Iprojections 8U andA 82"extend beyond the k-'eyprojections 64", 665; 'B8 and 10has isshown in Fig-'3 2. The rearward endsQftheslQts Eiland 62 are `provided with a portion of reduced'width presenting shoulders. |53r and |.55'.adapted to engage the-portion ofthe projectionsv and 82` which extend beyond the projections l'Land 10. These shoulders |53 and; |55; are so locatedthat `disengagement takes place substantially. at the 100.-. siti'onin'which'the sear latches the bolt 20I in its rearward position. The screw 52 continues to operate unt-il the engagement of the projections -88 and 82, with the shoulders |53 and |55, has pulled the ball cam 18 lout of the nut 58 sufficiently far that the ball cam 18 no longer serves as the periphery of the helical portion of the ball race. T'his permits the balls to move out against the inner wall of the ball housing 58, thus vpermitting ythe balls '|16 to leave the thread grooves of the screw 52.

f When the bolt 28 is carried to its rearward position the time delay switch |21 will be opened thus deenergizing the motor 46 and stopping the rotation of the screw 52. The shoulders |53 and |55 must be so positioned that the ball cam 18 is disengaged from the ball 16 before the motor 46 -is deenergized or at least before the rotation of the screw is completely stopped. If there is considerable inertia in this screw and motor Ias sembly, the motor 4'5 may be deenergized before the cam 18 is disengaged and the inertia may be relied upon to keep the screw 52 in rotation until the ycam 18 is disengaged. In this rearward movement of the nut 58, the spring 34 is compressed thus cooking the gun so that it is prepared to resume firing immediately.

If the trigger switch |43 is kept closed, the sear 22 will not hold the 4bolt 28 and the bolt as well as the bushing 32 and the ball bearing nut 58 will be rapidly carried to the forward position. To cushion the return of the ball bearing nut 58, there is provided a spring guide ferrule |51 which surrounds the extension of the screw 52. This ferrule |51 is slidably mounted on the shaft portion of the screw 52 within a recess in an extension of the bearing 54. The end of the sleeve 56 also extends into this recess and between it, and the ferrule |51 is a compression spring |59 which with the ferrule |51 acts as :a buffer Ito absorb the inertia of the ball bearing nut 58. The forward end of the screw 52 has no threads land in order to support the nut 58 the shaft portion is provided with an enlarged cylindrical portion I-EI which guides the portion of the nut 58 beyond the threads upon the screw 52.

v The inertia of the ball bearing nut 5'8 forces the spring guide vferrule |51 back into the recess and in this action the projections 88 and 82 of the lball cam 18 engage the edges of the recess in the bearing 54 to cause the ball cam 18 to be returned to the position shown in Fig. 1--B wherein the balls in the helical portion of the ball race are again forced into engagement with the screw 52. The portion of the screw 52 with which they are forced into engagement has no .threads but the balls are pushed to the beginning of the threaded portion by the spring |59 which, after the impact, moves the nut 58 rearwardly until the balls 1'6 engage the beginning of the threaded portion of the screw 52. The ball bearing nut 5B will remain in this position throughout al1 normal firing periods and idle periods of the gun. It will not again be used until the .time delay switch |21 should again be closed.

While I have described my releasing ball bearing nut and screw as applied to the charging or cooking of a machine gun it should be obvious that there are many other possible applications wherein it is desired to use a ball bearing nut and to release it at one point of the screw and again reengage it at another point in its traverse of the screw. The ball cam 18 may be provided with a spring latch ||63 formed of a spring steel disk having a projection formed therein which is mounted in a recess in the forward ball guide and is adapted to project into two spaced apertures |65 in the projection '82 of the ball cam 18. This prevents the ball cam 18 from moving out of the position to which it is forced. Thus the jarring eifect of the ring of the gun will not .be able to disturb the position of the ball cam 18.

While the form of embodiment of the invention as herein dis-closed constitutes a preferred form, it is to be understood that other forms might be adopted, as may come within the scope of the claims which follow.

What is claimed is as follows:

l. In combination, a sleeve provided with a slot, a screw within the sleeve, a ball bearing nut upon the screw having a projection extending within and guided by the slot= said nut having means forming an endless ball race, one of the confining surfaces of the race having a removable portion, a plurality of balls in said race in engagement with a thread groove in the screw, an operating means extending from said. removable portion into said slot, said sleeve having a transverse wall portion forming a part of said slot for engaging and operating said removable portion relative to the remainder of the nut to permit thel balls to move out of engagement with said thread groove.

2. In combination, a screw, a .ball bearing nut upon the screw including means forming an endless ball race having its major portion in the shape of a helix, a plurality of balls substantially filling said ball race, said nut being provided with suincient clearance space adjacent said race to permit the .balls to disengage themselves from the thread groove of the screw, the connning surfaces of the race including a removable portion having a rst position for normally holding the balls in engagement with a thread groove of the screw and a second position in which it is removed from the ball race to permit the balls to disengage themselves from the screw, said removable portion when in the first position rbeing located in said clearance space for blocking olf said clearance space from the race to confine the balls in a thread groove of the screw and when in its second position vaca-ting the clearance space adjacent to the ball race and merging the space and the race to permit the balls to protrude into said clearance space and disengage themselves from the screw.

3. In combination, a screw, a ball bearing nut upon the screw including means forming an endless ball race having its major portion in the shape of a helix, a plurality of balls substantially filling said lball race, said nut being provided with suflicient clearance space adjacent said race to permit the balls to disengage themselves from the thread groove of the screw, the confining surfaces of the race including a removable portion having a first position for normally holding the balls in engagement with a thread groove of the screw and a second position in which it is removed from the ball race to permit the balls to disengage themselves from the screw, said removable portion when in the first position being located in said clearance space for blocking ofi said clearance space from the race to confine the balls in a thread groove of the screw and when in its second position vacating the clearance space adjacent to the ball race and merging the space and the race to permit the balls to protrude into said clearance space and disengage themselves' fromithe'screw, means rior'rotating4 the'screvf'rela-J tivefto-the nur.mofeaus'etreiative' axial movements andsmeanspiectivewhen? thvnut reaches a preer determinedvfaxial position'. relative tofthe sorevv` forzremoviugisaid :removable-portion'ffromthe rst position-forming ai portion .of the-confining sur-*i faces for th'e'.' bait racezto its." secondi postin'z to release tli'e balls'ffromrengagementfwithfsaid screw'.

4. In combination, a screw, a ball bearing nut? upon.'the1screw"includingfmeansforming an endless': balli. race:A having: its major: po'rtion in the' shape?. off'ahelixaa pluraiitylio'f ballssubstantiallyl liin'g "said:bauxl rase; said nut". being provided? with suicient clearances-pace adjacent'said'fra'ce: to permit the balls.'.tof.dserrg'agef'themselves from ai -tlrread groove"of"th`e s'crevvfthe confining surfacesieof'the' race' including' a removable portion having' a first' p'osition'rrrnormally holding' the baillse in engagement'wit'h aithrea'd'groove of the' screvvfan'dA a second'- position iniwhich it is re-A trude into said clearance space and disengagez:

themselvesi'from' the screw, means for' rotating th'efscrevv-relativefto' the-'mut to cause'relativeanaal: inovemenasmeans eftective when the nut` reachesfa predetermine'diax-ial position relative to' thezscrew- -for removing said. removable portion from: the first position forming'. a' portion of' the confining-'surfaces ofithez; balirace to its second positionr'to' releasei-the" bals fromi engagementy With' saidA screw, spring' means for propelling the nut upon-release; 'andmeainsT for restoring said removableV portion? to the`first'po'siti'on where it forms: a portion of th'efc'onning: surfaces of they ball race4 for reeengagi'ngf the balls' with the threadfgfroove.l

In combinatiom-a' screma ba'llbearing nut upon the screw includingtmearis'forming an endless' ball' race having its'm'ajoi' portion in' the shape ofiar hel-ix; aplurality of balls substantially lling said-ball'race,` said nutbeirrgzprovided with sufcient clearancespacet adjacent saidem'ovable portionr to permit the "-ballsl'tof/disengage' themselves from athrea'dgroove of'th'e screw, the' conning surfaces of the race including a removable portion having a` rstpo'sitionfornormally holdingftherba'lls in Vengagement', with a thread groove' ofthe screwfan'd asecon'dpositi'on in which ithis removedfromrfthe'balli race to permit the ballsy to disengage' themselves'from the screw, saidremovable portion when in the rst position being: located between' said' clearance space and the Vball raceforY block-ingv orsaid clearance space from the. racev toconne the'- balls in. a thread groove of the screwfand: Wh'en'iin its second position openingthe' clearancespace to the ball race and merging the spacefandttherace to permit the balls'to' protrude.' into' sadi clearance space and disen'gage themselves from the' screw, means for rotating" the" screw relative' to the nut to cause relativeA axialv movement', means effective' when' thel nut reaches* a predetermined' axial position relative 'to thesc'rew 'for' removing4 said remov able" portion' from the' first 'position` forming a portion of tne'connmg's'urface's ofthe ball race` touts second` posit-ionvto' release the-balls from engagementwi'tii Tsaidscrew;"-spzrin'gmeans fors propelling the -fnut upon' release;=.fand'fmeans'. ef fe'ctive". when thel Anut' reachesj -a second f predeterx-v mined. position'A fori restoring; said removable pore1 tion into the rst positionr'in 'whicl'iwitfformsa' portionof the'conning surfaces 'of' the bafllnraceV for'reeen'gaging the balls'iwithfthethread groove;l

6. ln. combinatinga screw, a ballibearing nut upon'\the screw' including means forminganiende': less ball. race' yhaving* its major portionl in :ther shape of a helix, a plurality'oflb'alls substantially` illing'saidiballfrace,- said nut beingprovidedtwith suiicient clearance. space `adjacerrttsaid race'ftoz permitxthe' balls to 'disen'gage themselves"from thethread groove' ofl'the screw, the 'coniningx sur; facesvof the' racefino'luding airemovableuportion: having a rst positi'omffor' normallyholdinglthe? ba'llszinengagement vwith a threadr groove\'off.tli= screw, and'V a secondipositi'onfin Whiclfrrit is'-.re` moved from the :ballrace to permit theiballsfto; dis'engage themselves' from '.theiscrevv,A said: re.= movable portion; when in.: the first positionf being? located in* said vclearance space. forcxblockingr of!! saidl clearance spacerfromthe: race: to' confine Ithesbasllszin' a` threadrgrooveofzthe :screw` and` wheua. innits second position Yvacatin'glfthe' :clearan'cef space adjacent to thesbal1fracetand mergingit'he space and ythe 'race to ipermitv'thesballs Ito? protrude. into'.- said clearance: space r'andz. disengage. tlienriselves` from the screw;saidlremovableiporw tion having operating means projecting `fromtthe nut', means for rotatingftherscrewrelativeitoith nut to. causeA relative' axial movementandiseparate*V projectingmea-ns1 proj ecting"A into' zthe fpatlr1 of `nuwement'oi saidi operating :means ;for:"mov;'

: ing saidy removable'lportio'n fromy on'e"of'.its'posie tionsto another;

7. In combination, ascreW;.a1ball' bearingmutr upon the .screw including. mean-sf forming ran.' end-i less..l bal-L race `having its major'fportion intheA shape 'of'a helix;'said'-nut havingr'a clearance? space surrounding :thev loall'irace'r a pluralityof balls substantiallyvillingfsaid ballrracthe'con-i ning surfaces of tha-race includingian axially.' movable sleeve'portion having aA firstI position? .in which it'fis .locatedinr said clearance spac'eifon normally holding the balls in engagement Withl-a thread groove of "theft screw and' 4a secon'dfpo'sition-inI which it'is removed'from' the periphery of the *ball race-andfsaidclearanc`e space' toperie mitthe balls to'` protrude intoI saidy clearance space anddisengag-e'themselves f from the' thread groove of'the screw.

8. In combination; a screw; a ball be'aringfnut' upon the screw including nieans'forminganendlessl balli race having: itsV major' portion in: th'e shapefof a,` helix, 'sa-idrnut-having af clearance' space` surroundingfthefball race, a pluralityi'fof? bal-ls substantially lllingsaid ball race,` the con;-v ning surfaces' of4 lthera'ceincluding an axially movabley sleeve port-ion^ having f a rst" position" inrwhich' it is located? in said clearance! spaceion normally holding the baills fin'V engagementffwitlr a thread groove ofthescrevz and a second posi'-A tionf inWhich-it is removed fromthe periphery? ofI the -balL race and said' clearancel space 'to per:' mit the balls to protrude into said clearance 'space and. disengage themselvesffrom' the t'lireadsgroove of the screw; said sleeve portion' beingfprovided with: a cainmingv edge vfor c'ammin'g the' balls 'out of' the* y'clearanme"' space' into f engagement? Witl'ifaf thread'fin' the screw."

9. In combinationg' a screw, a ba'll bearing nut' upon lthe screw'- including VmeansA forming an endl' less ball race" having' its' major" portion" in the shape" off-a' helix,' said' Ynut having" 'a' 'clearance 'space Surrounding the ball race, a plurality of balls substantially lling said ball race, the confining surfaces of the race including an axially movable sleeve portion having a first position in which it is located in said clearance space for normally holding the balls in engagement with a thread groove of the screw and a second position in which it is removed from the periphery of the ball race and said clearance space to permit the balls to protrude into said clearance space and disengage themselves from the thread groove of the screw, said sleeve portion being provided with an edge having a contour similar to the contour of the ball race, saidedge of said sleeve portion being provided with a camming surface for camming the balls out of the clearance space into engagement with a thread groove in the screw.

10. In combination, a screw, a ball bearing nut upon the screw including means forming an endless ball race having its major portion in the shape of a helix, said nut having a clearance space surrounding the ball race, a plurality of balls substantially iilling said ball race, the conflning surfaces of the race including an axially movable sleeve portion having a rst position in which it is located in the clearance space for vnormally holding the balls in engagement with a thread groove of the screw and a second position in which it is removed from the periphery of the ball race and said clearance space to permit the balls to protrude into said clearance space `and disengage themselves from the thread groove of the screw, said sleeve portion being provided with a recessed portion extending between the two ends of the helical portion of the ball race `when it is located in its first position for permitting the return of the balls from one end of the helical portion to the other end of the helical portion of the ball race.

11. In combination, a screw, a `ball bearing nut upon the screw including an outer housing having a cavity extending through it, a set of sleeve portions within said housing portions, said sleeve portions being of substantially the same diameter and being located in alignment, the adjacent ends ofthe sleeve portions being spaced from each other a uniform distance throughout, the major portion of each `of the ends being in the shape of a helix corresponding to that of the screw to form a ball race, a plurality of balls substantially filling the race formed between the ends of the set of sleeve portions, said housing portion having a clearance space surrounding the adjacent ends of the sleeve portions to permit the balls to protrude therein and disengage themselves from the screw, said nut being provided with an axial movable sleeve portion slidably mounted upon said set of sleeve portions having a first position l-ocated in said clearance space surrounding the adjacent ends of the set of sleeve portions to conne the balls in a thread groove of the screw, said axially movable sleeve portion having a second position in which it is axially removed from the clearance space surrounding the ball race to permit the balls to protrude into said clearance space and disengage themselves from the screw.

12. In combination, a screw, a ball bearing nut upon the screw including an outer housing having a. cavity extending through it, a set of sleeve portions within said housing portions, said sleeve portions being substantially the same diameter and being located in alignment, the adjacent ends ci the sleeve portions being spaced from each other a uniform distance throughout, the major portion of each of the ends being in the shape of a helix corresponding to that of the screw to form a ball race, a plurality of balls substantially lling the race formed between the ends of the set of sleeve portions, said housing portion having a clearance space surrounding the adjacent ends of the sleeve portions 'to permit the balls to protrude therein and disengage themselves from the screw, said nut being provided with an axially movable sleeve portion having a first position located in said clearance space surrounding the ball race to confine the balls in a thread groove of the screw, said axially movable sleeve portion having a second position in which it is axially removed from the clearance space surrounding the ball race to permit the balls to protrude into said clearance space and disengage themselves from the screw, said axially movable sleeve portion being axially movable relative to said outer housing and having an operating portion protruding from the nut so that it can be axially moved relative to the nut to controly the confining of the balls in a thread groove of the screw.

13. In combination, a screw, a ball bearing nut upon the screw including an outer housing having a cavity extending through it, a set of sleeve portions within said housing portions, said sleeve portions being of substantially the same diameter and being located in alignment, the adjacent ends of the sleeve portions being spaced from each other a uniform distance throughout, the major portion of each of the ends being in the shape of a helix corresponding to that of the screw to form a ball race, a plurality of balls substantially filling the race formed between the ends of the set of sleeve portions, said housing portion having a clearance space surrounding the adjacent ends of the sleeve portions to permit the balls to protrude therein and disengage themselves from the screw, said nut being provided with an axially movable sleeve portion normally located in said clearance space surrounding the ball race to conne the balls in a thread groove oi the screw, said axially movable sleeve portion having a second position in which it is axially removed from the clearance space surrounding the ball race to permit the balls to protrude into said clearance space and disengage themselves from the screw, said axially movable sleeve portion being axially movable relative to said outer housing and being provided with a camming edge for camming the balls out of the clearance space into engagement with a thread in the screw.

14. In combination, a screw, a ball bearing nut upon the screw including an outer housing having an axially extending cavity, a set of sleeve portions within said housing portion, said sleeve portions being of substantially the same diameter and being located in alignment, the adjacent ends of the sleeve portions being spaced from each other a uniform distance throughout, the major portion of each of the ends being in the shape of a helix corresponding to that of the screw to form a ball race, a plurality of balls substantially lling the race formed between the ends of the set of sleeve portions, said housing portion having a clearance space surrounding the adjacent ends of the sleeve portions to permit the balls to protrude therein and disengage themselves from the screw, said nut being provided with an axially movable sleeve portion normally located in said clearance space to confine the balls in a thread groove of the screw, said axially movable l #sleeve :portion 'having a ise''ond apositioniin which lit is axially 4renxoved from-'the-'clearance space @to perrnitthe ballstofp'rotrude into saidlclearance is-pafce fan'ddisengage themselves from the screw,

said axially imovablefsleeve `fportion being `axially g -moveible relative toisaid'iouter 'housing :and being provided withy a' cammingwedge having a hellical `contour sin`1i1ar'toithe1he1ical contour fof the `bail lrace Jand aideepfreeessed'portion betweenI the -le'nds of the Yiielie'al contour portion permitting ff-the"=return-iof u:balls-f'fromfone end of the helical portionoffthe ballfrcetolthe other end thereof.

"15;'In combination, sa screw having its" thread "interrupted adjacent-.None end, a freleasable nut Uupon the'fs'crewfinol'uding 'operating lmeans hav- '='termined-ldistancfron'theinterrupted portion. Y

Veeiew.

adjacent 1 said penilxheral 'portion toi-permitirme :balls Ito ,disengagei @themselves from a thread groove .of whe ifscrew;.fsaidxremovable 4:peripheral :portion Ywhenl in thef yposition :forming A,the :pevripheryfoffzthe ,confining surfaces;of the :ball'maice being located in said clearance space for blocking nii said clearancegspace-:to:tconne fthe Vballs in a." thread 'groove :.ofthe ,screw rand-,1in ,tanotherrpnfsition ,opening "the i tclearanoexispace :'to the ball vraieerand mergingrthezspa-,cezandflthe .race toner- Init fthe balls tofdisengage :themselvs :from "the screw.

CLARK.

. #REFERENCES aCIZlfFD The following references `Sayre'of/record'intthe iefof'this patent:

- Number #Name "Date f'64'5j608 :Schalke EM-M120, `1900 "676,044 -Locke June 11,31901 2,1:38784 ffCooiey "1Nov`. 29,"1938 .2;14'gli78 iDyer L Dec.4 27, 1938 2,32233817 A"3:"itriey --.Y i.une"22,'1-943 "FOREIGN" PTEN TS Number Country *Date 

